SRS8104545 SAMN17509343 1904483 sheep gut metagenome bioproject 601636 PRJNA601636 host Ovis aries isolate negative control age fetus sex male tissue cecal content collection_date missing geo_loc_name missing lat_lon missing BioSampleModel Metagenome or environmental SRS8104546 SAMN17509344 1904483 sheep gut metagenome bioproject 601636 PRJNA601636 host Ovis aries isolate positive control age fetus sex male tissue cecal content collection_date missing geo_loc_name missing lat_lon missing BioSampleModel Metagenome or environmental